Carburators

 2 stroke Carburetors works the same way as  4 stroke carburbtors do. There are fuel lines that go into the float bowl,  the float valve inside the float bowl controls how much fuel that can go into the float bowl. The fuel then enters a jet that jet sprays the fuel into a venturi which adds pressure so the fuel and air mixes together. Above the jet is the air intake, The  air/fuel mixture then passes though the throttle plate. When the throttle plate is fully open it lets as much fuel as it can pass though. The throttle plate is never fully closed because if it was the motor would not iddle witch means it will not run. After that the muxture goes down the carb throat and into the combustionchamber.



Emulsion TubesThe air from the air bleeds enters the main circuit through the emulsion tube. The emulsion tube has a series of small holes from top to bottom, and it is through these holes that air enters the main circuit. At low engine speeds, when fuel demand is low, these holes are submerged in fuel, and so no air can flow through them. As engine speed increases, the fuel level in the float bowl drops, uncovering these holes, and allowing air from the bleeds to enter the main circuit, thus leaning the mixture. As the engine speed increases further, the fuel level in the float bowl continues to drop. This uncovers even more of the holes in the emulsion tube, which makes the air bleed have a greater effect on the mixture


Manual and automatic choke
A manual choke is opparate manualy by pulling a lever that closes the choke buterfly that is at the beggeing of a carburtor. A automatic choke is controled by a thremostic coil which the buterfly sharft is attcaed to. When the heat for the motor running the coil releases and the choke is then opened.

Float valve
The float valve is there to control the amount of fuel that can enter the venturi. As fuel getts used the level of fuel in the float boul drops causing the float to drop and open the needle valve letting more fuel into to the float boul.
Float valve

Mechanice lift pump
A mechanide lift pump is used to pump fuel into the carburtor. A mechanice lift pump is bolted to the head or to the block. This is because the camshaft has an extra lobe on it witch pushes on the lift pump rocker arm. When the pistons travel down to bottom dead centre it sucks fuel into the mechanice lift pump. When the pistons travel to top dead centre the fuel is forced out of the lift pump into the carburtor.


Vacuum fuel pump
The carburtor is not strong enoff to suck fuel into the carburtor so there is a vacuum pump just befor the carb to pump the fuel into the carb. The vacuum pump work by diaphrame.  The diaphrame works on piston strokes. There is also a one way valve in the pump witch make sure the fuel can only go one way and allows no air in the system.
What presure did you get from these pumps?? you gett around 2 - 4 PSI


Diffrents between diesel and petrol
Diesel runs on C.I compression igintion, this is compression to heat, there is enough heat and compreesion to cause an explotion forcing the pistons down.
Petrol runs on S.I spark igintion, petrol is highly flamable so with a small spark it will egint easly. forcing the pistol down.

Fuel cut off switch
The fuel cut off switch works on a copper coil causing a magntice force controling the swith.

What is the four stroke cycle
Intake,
compreesion,
power,
exhaust,

what dose S.I mean?
spark igintion

What dose C.I mean?
cpmpreesion igintion

When taking a carb apart what should you be really carefully with?
You have to be extra carefully and not turn the arb upside down. when turning it upside down the float needle valve can come out and wont go back in propally

When dismantling a carb what precaution should you take? do not turn it upside down because the small springs and valves will change position/alinement.
How does a bimetallic spring work in a automatic choke work? A bimetallic spring that helps with cold starting.when the engine is cold the sping holds the butterfly valve closed, as the engin heats up it slowly opens the valve producing a progressivly leaner fuel mixture. At the same time the high idle gradulay drops back to normal, when the engin is warm the butterfly valve will be fully open, ( standing up) producing the right mixture of air and fuel for the warm engine.

What is the purpose of the venturi and how does it work? it works on the same principles as a aeroplane wing - so it bottlenecks to make the air presure rise and flow faster and the fuel an air to mix more effectively